CN107667122A - The method for aoxidizing the material based on starch - Google Patents

Abstract

A kind of method for being used to aoxidize the pulverulent material containing starch, it includes following step one by one：By the pulverulent material containing starch and hydrogen peroxide (H₂O₂) aqueous solution mixing, and add ammonia spirit in the resulting mixture and it is reacted with the mixture；The step of this method can also include said mixture is further dried to obtain the pulverulent material containing oxidized starch；This method can advantageously comprise following steps：The continuous stream supply of pulverulent material containing starch is included into the first reactor (R) of cylinder tubular body (1) and rotor, the rotor is arranged in cylinder tubular body, it includes being provided with the axle (8) for being radially therefrom prominent element (9), and rotated with the speed more than or equal to 50rpm, the continuous stream of aqueous hydrogen peroxide solution is supplied into the reactor；The continuous stream and hydroperoxidation of pulverulent material containing starch；The continuous stream of wet powder is discharged from the discharging opening (7) of first reactor, and continuous stream supply is included into cylindrical tubular body (101) and the second reactor (R') of rotor, the rotor is arranged in cylinder tubular body, it includes being provided with the axle (108) for being radially therefrom prominent element (109), and is rotated with the speed more than or equal to 50rpm；By the continuous stream supply second reactor (R') of ammonia spirit；The continuous stream of the wet-milling containing oxidized starch is discharged from the discharging opening (107) of second reactor；Wet-milling drying to water content is less than or equal to 20 weight %, so as to obtain the pulverulent material containing oxidized starch.

Description

Process for oxidizing starch-based materials

technical field

The present invention relates to a method of oxidizing starch-based materials, in particular meal obtained from cereals and starch.

Background technique

Oxidized starches are used in all industrial fields where additives with good film-forming and adhesive properties are required.

In the food industry, oxidized starch is a thickener that allows (E-1404) to be used, for example, in creams, sauces and sweet products, while in the paper industry it is used as an additive to increase the strength of paper, with It is used to improve its printing performance and improve the retention of cationic additives, and as a binder for papermaking fibers. WO 00/15670 describes the use of oxidized starch as binder for coatings.

Through oxidation, the viscosity of starch in solution or dispersion decreases, and the average molecular weight of starch decreases.

Oxidation of starch is usually carried out using alkaline hypochlorite or peroxide as oxidizing agent.

Oxidation using alkaline hypochlorite is described, for example, in application WO 03/018638.

Oxidation using a peroxide such as hydrogen peroxide (oxidized water) is usually performed with a metal catalyst such as copper, iron or manganese.

Oxidation using hydrogen peroxide and Cu ²⁺ is described, for example, in application WO 00/15670.

These known methods have the disadvantage of an unpleasant odor and residues of alkali metal salts in the final product in the case of alkaline hypochlorites and, in the case of use of divalent copper or iron compounds, the disadvantage of reducing starch The disadvantages of whiteness and the presence of copper and iron salt residues. This makes the oxidized starch obtained unsuitable for use in the alimentary or pharmaceutical industries.

In view of the above-mentioned disadvantages, the problem underlying the present invention was to provide a process for the production of oxidized starch which does not lead to the presence in the oxidized starch of unpleasant odors or metal compound residues which lead to gelatinization of the starch or its quaternization. loss of ammonification properties and, in particular, the method does not involve any risks to the health of operators associated with currently used reagents.

According to another aspect of the invention, the invention relates to a method of oxidation of a starch-based material consisting of cereal meal.

In this respect, WO 2014/027139 discloses a process for oxidizing the starch fraction of cereals in the presence of a catalyst containing Cu ²⁺ or Fe ²⁺ , the purpose of which is to reduce the gluten content comprising proline, by The starch portion of this cereal is subjected to the action of an oxidizing agent selected from hydrogen peroxide, ascorbic acid and titanium oxide.

In this case, there is the disadvantage of changing the color of the meal in the final product and the persistence of metal compounds which are undesirable in products intended for human or animal food use.

Contents of the invention

According to the invention, the above-mentioned problems are solved by a method for oxidizing starch-containing materials carried out in the absence of any metal compounds and comprising the following steps one by one:

a) providing powdery material containing starch;

b) mixing said powdered material with aqueous hydrogen peroxide (H ₂ O ₂ ); and

c) Adding an aqueous solution of ammonia to the mixture thus obtained and allowing it to react with said mixture.

The final mixture can be finally subjected to a drying step to obtain a powdery material containing oxidized starch.

The above-mentioned starch-containing pulverulent material is selected from the group consisting of starches of different origin (for example from corn, potato, wheat, cassava, rice and legumes), meal from cereals, wherein cereals are in particular wheat, rice, corn, Barley, rye, oats, buckwheat, amaranth, and quinoa, and meals from legumes, especially beans, peas, chickpeas, broad beans, lentils, lupines, sweet peas, and soybeans ( soybeans).

The reaction is usually carried out at room temperature, preferably at a temperature of 15 to 25°C.

The w/v concentration of the above aqueous hydrogen peroxide solution is preferably between 5% and 20%.

The w/v concentration of the ammonia solution is preferably between 5% and 20%. The weight ratio between the starch-containing powdery material and the aqueous hydrogen peroxide solution is usually between 3 and 20.

The weight ratio between the aqueous hydrogen peroxide solution and the aqueous ammonia solution is usually 1 to 10.

According to the method of the present invention, the moisture content of the powdery material containing oxidized starch obtained at the end of the reaction is preferably less than or equal to 20% by weight, preferably 5 to 15% by weight, of the total weight of the powdery material through the above-mentioned drying step.

The reaction according to the method of the invention is preferably carried out in a reactor in which the starch-containing powdery material is brought into intimate contact with an aqueous solution of the reagents.

A reactor particularly suitable for carrying out the process of the invention consists of a reactor comprising a cylindrical tubular body with a horizontal axis, having at least one opening for the introduction of the reagents and at least one opening for the discharge of the final product an optional heating or cooling jacket for bringing the temperature of said tubular body to a predetermined temperature; and a rotor arranged in the cylindrical tubular body and comprising a shaft provided with elements projecting radially therefrom.

When using such a device, according to a first embodiment of the invention, the method of oxidizing a starch-containing powdery material comprises the following steps:

a) feeding a continuous flow of starch-containing powdery material to a first reactor of the type described above, wherein the rotor rotates at a speed greater than or equal to 50 rpm to disperse the continuous flow of starch-containing powdery material into the Particle flow of the above materials;

b) feeding a continuous flow of aqueous hydrogen peroxide into said reactor together with said continuous flow of starch-containing powdery material, said continuous flow of aqueous hydrogen peroxide being dispersed into a flow of tiny droplets by said rotor;

c) centrifuging the granules and the droplets against the inner wall of the first reactor to form a highly turbulent, dynamic, thin tubular fluid layer in which the granules of starch-containing pulverulent material are mixed with the hydrogen peroxide droplets of the aqueous solution are held in mechanically intimate contact by radially protruding elements of said rotor, while being propelled towards the outlet in substantial contact with said inner wall of the reactor;

d) reacting the starch-containing powdery material and hydrogen peroxide in said thin layer as it advances towards the discharge opening substantially in contact with said inner wall of the turboreactor;

e) discharging a continuous flow of wet powder from said outlet and supplying said continuous flow to a second reactor of the type described above, wherein the rotor rotates at a speed greater than or equal to 50 rpm;

f) A continuous flow of ammonia solution is supplied to the second reactor together with the continuous flow of wet powder, and the continuous flow of ammonia solution is dispersed into a flow of tiny droplets by the rotor;

g) centrifugation of the continuous flow against the inner wall of the second reactor by the action of the radially protruding elements of the rotor such that they are oriented in substantial contact with the inner wall of the second reactor The outlet moves;

h) discharging a continuous flow of wet powder containing oxidized starch from said outlet;

i) drying the wet powder until the water content is less than or equal to 20% by weight, so as to obtain a powdery material containing oxidized starch.

The temperature of the inner wall of the above-mentioned first reactor is preferably maintained at room temperature, conveniently at 15-25°C.

The temperature of the inner wall of the above-mentioned second reactor is preferably kept at room temperature, conveniently at 15-25°C.

The w/v concentration of the above aqueous hydrogen peroxide solution is preferably between 5% and 20%.

The w/v concentration of the ammonia solution is between 5% and 20%.

The ratio between the flow rate of the stream of aqueous hydrogen peroxide supplied to the first reactor and the flow rate of the stream of starch-containing pulverulent material supplied to the reactor is preferably between 1:20 and 1:5, conveniently between Between 1:15 and 1:8.

The ratio between the flow rate of the ammonia solution stream supplied to the second reactor and the flow rate of the wet powder material stream discharged from the first reactor is preferably between 1:20 and 1:5, conveniently between 1:15 to 1:8.

The residence time of the starch-containing pulverulent material in the first reactor is generally between 30 seconds and 20 minutes, depending on the degree of oxidation to be obtained, which increases with the residence time.

The residence time of the wet powder in the second reactor is typically between 30 seconds and 5 minutes.

The rotational speed of the rotor is preferably between 50 and 1500 rpm, advantageously between 150 and 500 rpm.

The aforementioned elements protruding radially from the shafts of the rotors of the first and second reactors can each be in the form of, for example, rods, vanes, V-blades or beaters.

According to an alternative embodiment, a reactor is used, wherein said reactor comprises a cylindrical tubular body with a horizontal axis, provided with a first opening and a second opening arranged near one end of said cylindrical tubular body for introducing reagents , a third opening arranged at a position between said first end of said cylindrical tubular body and an opposite end of said cylindrical tubular body for introducing a reagent, and at least one opening for discharging a final product; An optional heating or cooling jacket for bringing the temperature of said tubular body to a predetermined temperature; and a rotor arranged in the cylindrical tubular body and comprising a shaft provided with elements projecting radially therefrom.

When using the reactor, the method for oxidizing the starch-containing powdery material comprises the following steps:

a') A continuous flow of starch-containing powdery material is supplied to a reactor of the type described above through said first inlet, and the rotor rotates at a speed greater than or equal to 50 rpm to feed the continuous flow of starch-containing powdery material flow dispersed into a stream of particles of said material;

b') supplying a continuous flow of aqueous hydrogen peroxide solution to said reactor through said second inlet, said continuous flow of aqueous hydrogen peroxide solution being dispersed into a stream of tiny droplets by said rotor;

c') centrifuging the granules and the droplets against the inner wall of the reactor to form a highly turbulent, dynamic, thin tubular fluid layer in which the granules of powdery material containing starch are mixed with the aqueous hydrogen peroxide solution the droplets are held in close mechanical contact by the radially protruding elements of said rotor while being propelled towards the outlet in substantial contact with said inner wall of the reactor;

d') causing the starch-containing powdery material to interact with hydrogen peroxide in said thin layer when advancing towards the discharge opening substantially in contact with said inner wall of the reactor;

e') sending a continuous flow of ammonia solution into the reactor through the third inlet, the continuous flow of ammonia solution being dispersed into a flow of tiny droplets by the rotor;

f') by the action of the radially protruding elements of the rotor the continuous flow is centrifuged against the inner wall of the reactor so that they are directed towards the discharge in substantial contact with the inner wall of the reactor Mouth movement;

g') discharging a continuous flow of wet powder containing oxidized starch from said outlet;

h') drying the wet powder until the water content is less than or equal to 20% by weight, so as to obtain a powdery material containing oxidized starch.

Preferably, said third opening is arranged along a distance of approximately half of the length of said cylindrical tubular body.

The w/v concentration of the above aqueous hydrogen peroxide solution is preferably between 5% and 20%.

The w/v concentration of the ammonia solution is preferably between 5% and 20%.

The ratio between the flow rate of the stream of aqueous hydrogen peroxide solution supplied to the reactor and the flow rate of the stream of starch-containing pulverulent material supplied to the reactor is preferably between 1:20 and 1:5, conveniently between 1:15 to 1:8.

The ratio between the flow rate of the stream of ammonia solution supplied to the reactor and the flow rate of the stream of starch-containing pulverulent material supplied to the reactor is preferably between 1:20 and 1:5, conveniently between 1:15 and 1 : Between 8.

The residence time of the starch-containing pulverulent material in the reactor is generally between 30 seconds and 20 minutes, depending on the degree of oxidation to be obtained, which increases with the residence time.

The rotational speed of the rotor is preferably between 50 and 1500 rpm, advantageously between 150 and 500 rpm.

The aforementioned elements protruding radially from the shaft of the rotor may be in the form of, for example, rods, blades, V-blades or stirrers.

In both of the above embodiments, the reaction comprises a first stage of soaking together the starch-containing powdery material with aqueous hydrogen peroxide solution, followed by reacting the hydrogen peroxide-soaked powdery material with ammonia solution and activating the oxidation of the starch chains reaction.

Preferably, the above steps i) and h') of drying the wet powder are carried out by means of a turbo dryer comprising a cylindrical tubular body with a horizontal axis provided with at least one inlet and at least one outlet ; a heating jacket for bringing the temperature of said tubular body to a predetermined temperature; and a rotor disposed in the cylindrical tubular body and comprising a shaft having an element radially protruding therefrom.

Using the turbo dryer, the drying steps i) and h') are carried out:

j) said wet powder discharged from said reactor is supplied to said turbo dryer through said at least one feed port, the inner wall of turbo dryer is maintained at a temperature of at least 70° C. by said heating jacket, and the rotor Spin at a speed of at least 150rpm;

l) centrifuging and propelling the wet powder within a turbo dryer by the action of the rotor; and

m) Discharging a continuous stream of oxidized starch-containing pulverulent material having a water content less than or equal to 20% by weight from the outlet of the turbo dryer.

Optionally, at the same time as the aforementioned flow of wet powder is fed to the turbo dryer according to step j), a gas stream (preferably an air stream) heated to a temperature of at least 50° C. is also fed into the turbo dryer through the aforementioned at least one feed port. device.

The temperature of the inner wall of the turbo dryer is preferably maintained at 70-180°C, conveniently at 130-150°C.

The rotational speed of the rotor of the turbo dryer is preferably set at 300-1200 rpm.

The aforementioned elements protruding radially from the shaft of the rotor may be in the form of, for example, rods, blades, V-blades or stirrers.

The temperature of the gas stream fed to the turbo dryer is preferably between 50°C and 250°C, conveniently between 120°C and 150°C.

The residence time of the above-mentioned wet powder in the turbo dryer is usually between 30 seconds and 20 minutes, depending on the degree of drying containing the oxidized starch to be obtained, which increases with the residence time.

According to another of its aspects, the invention relates to a device for carrying out the method according to the above-mentioned first embodiment, comprising:

A first reactor comprising a cylindrical tubular body with a horizontal axis, with at least one opening for the introduction of reagents and at least one opening for the discharge of final product; optionally for bringing the temperature of said tubular body to a predetermined temperature A heating jacket or a cooling jacket; and a rotor arranged in a cylindrical tubular body and comprising a shaft provided with elements protruding radially therefrom;

A second reactor comprising a cylindrical tubular body with a horizontal axis, with at least one opening for the introduction of reagents and at least one opening for the discharge of final product; optionally for bringing the temperature of said tubular body to a predetermined temperature a heating or cooling jacket; and a rotor disposed in the cylindrical tubular body and comprising a shaft provided with elements protruding radially therefrom.

The apparatus may further comprise a turbo dryer comprising a cylindrical tubular body having a horizontal axis, having at least one inlet and at least one outlet; a heating jacket; and a rotor disposed on the cylindrical tubular body and comprising a shaft provided with elements projecting radially therefrom.

Additionally, the device can include:

A syringe device having a tubular body provided with an inlet fluidly connected to at least one outlet of a first reactor, and an outlet fluidly connected to at least one inlet of a second reactor; supported within the tubular body Blade or screw rotors.

An injector device having a tubular body provided with an inlet fluidly connected to at least one outlet of a second reactor and an outlet fluidly connected to at least one inlet of a turbodryer; blades supported within the tubular body or screw rotor.

According to another aspect, the invention relates to a device for carrying out the method according to the aforementioned alternative embodiment, comprising:

Comprising a cylindrical tubular body having a horizontal axis, it is provided with a first opening and a second opening for introducing a reagent arranged near one end of the cylindrical tubular body, A third opening for introduction of reagents at a location between the first end and the opposite end of said cylindrical tubular body, and at least one opening for discharge of final product; an optional heating jacket or cooling jacket; and a rotor, which Disposed in the cylindrical tubular body and comprising a shaft provided with elements projecting radially therefrom.

The plant may also comprise a turbo dryer as described for the plant for carrying out the method according to the first embodiment.

Furthermore, the apparatus may also comprise an injector device having a tubular body provided with an inlet fluidly connected to at least one outlet of the reactor and an outlet fluidly connected to at least one inlet of the turbodryer; supported on Blade or screw rotor within a tubular body.

According to another aspect, the present invention relates to a powdery material containing oxidized starch, which can be obtained by the method as described above from the group consisting of: starch from corn, potato, wheat, cassava, rice and beans, from such as wheat , rice, corn, barley, rye, oats, buckwheat, amaranth, and quinoa, and from grains such as beans, peas, chickpeas, broad beans, lentils, lupines, sweet peas, and soybeans ( obtained from the powdery material in the group consisting of coarse powder of soybeans).

When the starch-containing powdery material is formed from starch, the product obtained by the process of the invention is oxidized starch suitable for all the uses mentioned further above, given that the process according to the invention does not lead to the presence of any metals in the final product Facts of compound residues, especially recommended for food and pharmaceutical use. In fact, the excess hydrogen peroxide is completely deactivated by the ammonia, which then completely eliminates any residual ammonia in the wet powder discharged from the reactor in a subsequent drying step.

The oxidized starch obtained by treating starch of any origin using the method according to the invention is completely white and produces an aqueous dispersion/solution with a significantly lower viscosity than a solution/dispersion with the same concentration of starting starch.

When the starch-containing pulverulent material used in the method according to the invention is a cereal meal such as wheat flour or semolina, according to the method according to the invention it is possible to obtain a meal in which gluten is completely inactivated and is therefore also suitable for Food preparation for people with celiac disease or gluten intolerance. In this case, the meal obtained at the end of the process also does not contain metal compound residues and therefore has no color changes and is completely non-problematic from a food point of view.

Description of drawings

The advantages and features of the present invention will appear more clearly from the following description describing an example of a process for the cationization of starch, which is hereinafter provided with reference to the apparatus shown in Figures 1 and 2 of the accompanying drawings, purely by way of example way to provide this method.

Detailed Description

With reference to Figure 1, the apparatus for the process according to the invention comprises a reactor R essentially consisting of a cylindrical tubular body 1 closed at opposite ends by end plates 2, 3 and coaxially provided with a heating jacket (or cooling jacket) 4, which is intended to pass a fluid, such as diathermic oil, in order to keep the inner wall of the main body 1 at a predetermined temperature.

The tubular body 1 is provided with feed ports 5, 6, and a discharge port 7 for powdery material containing starch and aqueous hydrogen peroxide solution, respectively.

Inside the tubular body 1 is rotatably supported a rotor comprising a shaft 8 provided with radially protruding elements 9 in the form of blades arranged helically and oriented for centrifugation and simultaneously towards the discharge opening 7 Conveying the flow of powdery material containing starch and aqueous hydrogen peroxide solution and the wet powder formed after mixing the powdery material with hydrogen peroxide solution and reacting.

The electric motor M is used to operate the bladed rotor at a variable speed from 50 to 1500 rpm.

When discharged from the reactor, the above-mentioned wet powder is supplied to the injector device 51 via the pipe 11 communicating with the discharge port 7 of the reactor.

The body of the syringe device 51 has a tubular shape and is provided with an inlet 55 and an outlet 57 for receiving wet powder from the pipe 11 .

Inside the tubular body 51 is rotatably supported a blade or screw rotor 58 which gives the wet powder a forward thrust towards the outlet 57 which transfers the wet powder to the feed port 105 of the second reactor R'. The second reactor R', which has a completely similar structure to the first reactor described above, is not described in detail. Components of the second reactor that are identical to the first reactor are designated with the same reference numerals plus 100 . Only the feed port 106 is mentioned for supplying the aqueous ammonia stream.

The wet powder output from the discharge port 107 is supplied to the injector device 151 via the pipe 111 communicating with the discharge port 107 of the second reactor R′. Components of the injector device 151 that are identical to the injector device 51 are denoted by the same reference numerals plus 100 .

Through the outlet 157 of the injector device 151, the wet powder is discharged and fed to the turbo dryer T through the feed port 205.

The turbo dryer T basically consists of a cylindrical tubular body 201 closed at opposite ends by end plates 202, 203 and coaxially provided with a heating jacket (or cooling jacket) 204 intended to allow a fluid such as diathermic oil through so as to keep the inner wall of the main body 201 at a predetermined temperature.

The tubular body 201 is provided with openings 205 , 206 for introducing wet powder and hot air expelled by the injector device 151 , and an outlet 7 .

Inside the tubular body 201 is rotatably supported a rotor comprising a shaft 108 provided with radially protruding elements 209 in the form of blades arranged helically and oriented for centrifugation and simultaneously towards the discharge opening 207 conveys hot air and wet powder. The discharge port 207 is used to discharge the continuous flow of hot air and water vapor and the powdery material containing oxidized starch after heat exchange between the powdery material and the wall of the turbo dryer heated by the heating jacket 204 The wet powder obtained above was dried with a stream of hot air.

The stream of powdered material containing oxidized starch and hot air and water vapor is ultimately conveyed to vessel 18 for collection and separation of the steam and air also exiting the turbo dryer.

With reference to Figure 2, the apparatus for the method according to the invention, in an alternative embodiment thereof, comprises a first reactor R" consisting essentially of a cylindrical tubular body 301 passed at opposite ends by end plates 302, 303 is closed and coaxially provided with a heating jacket (or cooling jacket) 304, which is intended to pass a fluid, such as diathermic oil, in order to maintain the inner wall of the main body 301 at a predetermined temperature.

The tubular main body 301 is respectively provided with feeding ports 305, 306 for powdery materials containing starch and aqueous hydrogen peroxide solution, arranged near the end plate 302, and a feeding port 310 for aqueous ammonia solution is approximately equidistant from the end plate. Plates 302 and 303 are located along tubular body 301 , as well as outlet 307 .

Inside the tubular body 301 is rotatably supported a rotor comprising a shaft 308 provided with radially protruding elements 309 in the form of blades arranged helically and oriented for centrifugation and at the same time towards the discharge opening Step 307 is to send the powdery material containing starch, hydrogen peroxide aqueous solution and ammonia solution and the wet powder formed after mixing, and make the powdery material react with the hydrogen peroxide aqueous solution and ammonia solution.

The electric motor M is used to operate the bladed rotor at a variable speed from 50 to 1500 rpm.

When discharged from the reactor, the above-mentioned wet powder is supplied to the injector device 351 via the pipe 311 communicating with the discharge port 307 of the reactor.

The main body of the syringe device 351 has a tubular shape, and is provided with an inlet 355 for receiving wet powder from the pipe 311 , and an outlet 357 .

The plant also includes a turbo dryer T' that is completely similar to the turbo dryer T described further above and is therefore not described in detail. Components of the turbo dryer T' that are identical to the turbo dryer described further above are indicated by the same reference numerals plus 200 .

The plant finally comprises a container 18 for collecting the pulverulent material containing oxidized starch and separating it from the steam and air which are also output from the turbo dryer.

Example 1

A stream of powdered potato starch with a moisture content of 20% was fed continuously (100 kg/h) through the opening 6 to the reactor R in which the vane rotor 8 was rotating at a speed of 700 rpm. Simultaneously, a stream of 36 volumes of aqueous hydrogen peroxide corresponding to about 10.9% w/v was fed continuously (10 l/h) through the opening 5 .

The temperature of the inner wall is maintained at about 20°C.

At the feed inlet of reactor R, the starch stream is immediately mechanically dispersed into granules, which are immediately centrifuged against the inner wall of the reactor, where a dynamic, tubular, thin fluid layer forms. Simultaneously, the aqueous hydrogen peroxide solution supplied through the opening 5 is finely atomized by the blades of the rotor 8, and the blades of the rotor 8 also immediately centrifuge the obtained extremely fine droplets. The latter are thus introduced into a fluid layer of dynamic, tubular, thin starch granules, thereby enabling an intimate interaction between them.

After an average residence time in the reactor of about 30 seconds, the powder with a water content of 28% was continuously discharged from the opening 7 .

The wet powder is continuously fed into the reactor R' by means of the injector 51 through the opening 105 at a flow rate of 100 kg/h.

Inside the reactor R', the wall temperature was maintained at about 20°C, while the rotational speed of the vane rotor 108 was kept constant at 800 rpm.

A continuous flow of aqueous ammonia solution (10% w/v) was fed to reactor R' through opening 106 (flow rate 10 l/h).

After an average residence time of 20 seconds in the reactor, the wet powder with a moisture content of 35% was continuously discharged from the reactor through the opening 107 .

The wet powder is continuously fed into the turbo dryer T at a flow rate of 100 kg/h through the injector 151 through the opening 205 while being supplied with an air flow at a temperature of 100° C. (flow rate 500 m ³ /h) through the opening 206 .

Inside the turbo dryer T, the wall temperature was kept at 150° C., while the rotation speed of the vane rotor 108 was kept constant at 1000 rpm.

After an average residence time of 20 seconds in the turbo-dryer T, the powdered oxidized potato starch with a water content of 10% was continuously discharged from said turbo-dryer.

The viscosity of the 10% aqueous solution of the oxidized starch powder was measured to obtain a viscosity value of 10 cps, wherein the viscosity of the 10% aqueous solution of the starting starch powder was equal to 1450 cps.

Oxidized starch powder is completely white and odorless, and does not have any metal compound residues, so it is perfectly suitable for all uses of oxidized starch, especially food and pharmaceutical uses.

Example 2

Be that the cornstarch flow of the powder of 18% water content is continuously supplied (80kg/h) reactor R " through opening 306 ", and wherein blade rotor 308 rotates with the speed of 800rpm. Simultaneously, is equivalent to about 9.1%w/v excess Hydrogen oxide solution flow was continuously fed (10 l/h) through opening 305, and a continuous flow of 30 volumes of 9% w/v ammonia solution was continuously fed (10 l/h) through inlet 310. The temperature of the inner wall was maintained at about 20° C. .

After an average residence time in the reactor of about 30 seconds, the powder with a water content of 33% was continuously discharged from the opening 307 .

The wet powder is continuously supplied to the turbo dryer T' at a flow rate of 80 kg/h through the injector 351 via the opening 405 while being supplied with an air flow at a temperature of 100° C. (flow rate of 400 m ³ /h) through the opening 406 .

In the turbo dryer T', the wall temperature was maintained at 150° C., while the rotation speed of the vane rotor 108 was kept constant at 1000 rpm.

After an average residence time of 20 seconds in the turbo-dryer T', the powdered oxidized cornstarch with a water content of 10% was continuously discharged from said turbo-dryer.

The viscosity of the 10% aqueous solution of the oxidized starch powder was measured to obtain a viscosity value of 11 cps, wherein the viscosity of the 10% aqueous solution of the starting starch powder was equal to 1410 cps.

Oxidized starch powder is completely white and odorless, and does not have any metal compound residues, so it is perfectly suitable for all uses of oxidized starch, especially food and pharmaceutical uses.

Example 3

O-type wheat flour with a moisture content of 14% was continuously fed (100 kg/h) through the opening 6 to the reactor R in which the vane rotor 8 was rotating at a speed of 900 rpm. Simultaneously, a stream of 36 volumes of aqueous hydrogen peroxide solution corresponding to about 10.9% w/v was fed continuously (10 l/h) through the opening 5 . The temperature of the inner wall is maintained at about 20°C.

After an average residence time in the reactor of about 30 seconds, the powder with a water content of 27% was continuously discharged from the opening 7 .

The wet powder is continuously supplied to the reactor R' through the opening 105 by means of the injector 51 at a flow rate of 100 kg/h.

Inside the reactor R', the wall temperature was maintained at about 20°C, while the rotational speed of the vane rotor 108 was kept constant at 800 rpm.

A continuous flow of aqueous ammonia solution (10% w/v) was fed to reactor R' through opening 106 (flow rate 10 l/h).

After an average residence time of 20 seconds in the reactor, the wet powder with a moisture content of 34% was continuously discharged from the reactor through the opening 107 .

The wet powder is continuously supplied to the turbo dryer T at a flow rate of 100 kg/h through the injector 151 via the opening 205 while being supplied with an air flow at a temperature of 100° C. (flow rate 500 m ³ /h) through the opening 206 .

In the turbo dryer T, the wall temperature was kept at 150° C., while the rotation speed of the vane rotor 108 was kept constant at 900 rpm.

After an average residence time in the turbo dryer T of 20 seconds, the pulverulent oxidized starch with a water content of 13% was continuously discharged from said turbo dryer.

The flour obtained is white and odorless, and does not have any metal compound residues, so it is perfectly suitable for human consumption.

The gliadin contact of the flour obtained was determined by electrophoresis on a polyacrylamide gel (SDS-PAGE), resulting in a substantial absence of gliadin, indicating that the method according to the invention results in flour containing complete degradation of gliadin.

Therefore, this flour is especially suitable for people with celiac disease or gluten intolerance.

Claims (26)

1. A method for oxidizing starch-containing pulverulent materials, wherein said method is carried out in the absence of any metal compounds and comprises the following steps one by one: a) providing powdery material containing starch; b) mixing said powdered material with aqueous hydrogen peroxide (H ₂ O ₂ ); and c) Adding an aqueous ammonia solution to the mixture thus obtained and allowing it to react with said mixture. 2. The method according to claim 1, further comprising the step of drying the mixture of the step c), to obtain a powdery material containing oxidized starch. 3. The method according to claim 2, wherein the starch-containing powdery material is selected from the group consisting of starches of different origin, in particular starches from corn, potato, wheat, cassava, rice and beans, from Meals from cereals, especially wheat, rice, maize, barley, rye, oats, buckwheat, amaranth and quinoa; and meals from pulses, especially beans, peas, chickpeas, Broad beans, lentils, lupines, sweet peas and soybeans. 4. The method according to any one of claims 2 and 3, wherein the w/v concentration of the aqueous hydrogen peroxide solution is between 5% and 20%. 5. The method of claim 4, wherein the w/v concentration of the aqueous ammonia solution is between 5% and 20%. 6. The method according to any one of claims 2-5, wherein the weight ratio between the starch-containing powdery material and the aqueous hydrogen peroxide solution is between 3 and 20. 7. The method according to claim 6, wherein the weight ratio between the aqueous hydrogen peroxide solution and the aqueous ammonia solution is generally between 1 and 10. 8. The method according to any one of claims 2-7, wherein, the moisture content of the powdered material containing oxidized starch is reached to be less than or equal to the powdered material containing oxidized starch by the drying step 20% by weight of the total weight, preferably 5 to 15% by weight. 9. A method of oxidizing the starch-containing powdery material according to claim 2, the method comprising the steps of: a) A first reactor (R) is provided, comprising a cylindrical tubular body (1) with a horizontal axis, having at least one opening (5, 6) for the introduction of reagents and at least one opening for the discharge of final product (7); and optionally a heating or cooling jacket (4) for bringing the temperature of said tubular body to a predetermined temperature; and a rotor disposed in the cylindrical tubular body and comprising shaft (8) of the element (9), and a continuous flow of starch-containing powdery material is supplied to said first reactor, wherein the rotor rotates at a speed greater than or equal to 50 rpm to transfer said starch-containing powdery the continuous flow of material is dispersed into a stream of particles of said material; b) feeding a continuous flow of aqueous hydrogen peroxide into said reactor together with said continuous flow of starch-containing powdery material, said continuous flow of aqueous hydrogen peroxide being dispersed by said rotor into a stream of tiny droplets; c) centrifuging said granules and said droplets against the inner wall of said first reactor (R) to form a highly turbulent, dynamic, thin tubular fluid layer in which the granules of starch-containing pulverulent material are mixed with said The droplets of aqueous hydrogen peroxide are held in close mechanical contact by the radially protruding elements (9) of said rotor, while being propelled towards the outlet (7) in substantial contact with said inner wall of the reactor; d) the starch-containing powdery material and hydrogen peroxide react in said thin layer when advancing towards the outlet (7) substantially in contact with said inner wall of the turboreactor; e) discharging a continuous flow of wet powder from said outlet (7) and supplying said continuous flow to a second reactor (R') comprising a cylindrical tubular body (101 ) provided with at least one opening (105, 106) for introducing reagents and at least one opening (107) for discharging final product; optional heating jacket for bringing the temperature of said tubular body to a predetermined temperature or a cooling jacket (104); and a rotor (8) disposed in a cylindrical tubular body and comprising a shaft (108) provided with elements (109) protruding radially therefrom, wherein the rotor rotates at a speed greater than or equal to 50rpm rotate; f) a continuous flow of ammonia solution is supplied to the second reactor together with the wet powder flow, and the continuous flow of ammonia solution is dispersed into a flow of tiny droplets by the rotor; g) by the action of said radially protruding elements (109) of said rotor centrifuging said continuous flow against the inner wall of said second reactor (R') so that they are aligned with said second reactor The said inner wall substantially touches and moves towards the outlet (107); h) discharging a continuous stream of wet powder containing oxidized starch from the outlet (107); i) drying the wet powder until the water content is less than or equal to 20% by weight, so as to obtain a powdery material containing oxidized starch. 10. A method for oxidizing a starch-containing powdery material, the method comprising the steps of: a') A reactor (R") is provided comprising a cylindrical tubular body (301) with a horizontal axis, provided with a first opening (306) arranged near one end of said cylindrical tubular body for introducing reagents and a second opening (305), a third opening (310) arranged at a position between the first end of the cylindrical tubular body and the opposite end of the cylindrical tubular body for introducing a reagent, at least an opening (307) for discharging the final product; optional heating or cooling jacket (304) for bringing the temperature of said tubular body to a predetermined temperature; and a rotor disposed in the cylindrical tubular body and comprising a shaft (308) provided with elements (309) projecting radially therefrom and feeding a continuous flow of starch-containing pulverulent material to said reactor (R") through said first feed opening (306), the rotor rotates at a speed greater than or equal to 50 rpm to disperse the continuous stream of starch-containing powdered material into a granular stream of said material; b') supplying a continuous flow of aqueous hydrogen peroxide solution to the reactor through the second feeding port (305), the continuous flow of aqueous hydrogen peroxide solution being dispersed into a flow of tiny droplets by the rotor; c') centrifuging the particles and the droplets against the inner wall of the reactor (R") to form a highly turbulent, dynamic, thin tubular fluid layer in which the particles of powdery starch-containing material are mixed with the droplets of aqueous hydrogen peroxide are held in mechanically intimate contact by radially protruding elements of said rotor, while being propelled towards the outlet in substantial contact with said inner wall of the reactor; d') allowing the starch-containing powdery material to interact with hydrogen peroxide in said thin layer when advancing towards the outlet (307) substantially in contact with said inner wall of the reactor; e') supplying a continuous flow of ammonia solution to the reactor through the third feeding port (310), the continuous flow of ammonia solution being dispersed into a flow of tiny droplets by the rotor; f') The continuous flow is centrifuged against the inner wall of the reactor by the action of the radially protruding elements (309) of the rotor so that they are in substantial contact with the inner wall of the reactor Move towards the outlet; g') discharging a continuous flow of wet powder containing oxidized starch from said outlet; h') drying the wet powder until the water content is less than or equal to 20% by weight, so as to obtain a powdery material containing oxidized starch. 11. The method according to claim 9 or 10, wherein the drying steps i) and h') are carried out respectively by means of a turbo dryer (T, T') comprising a A cylindrical tubular body (201, 401) of the axis, which is provided with at least one inlet (205, 206, 405, 406) and at least one outlet (207, 407); for making the temperature of the tubular body a heating jacket (204, 404) to reach a predetermined temperature; and a rotor arranged in a cylindrical tubular body and comprising a shaft (208, 408) having elements (209, 409) protruding radially therefrom, - feeding said wet powder discharged from said reactor (R', R") into said turbo dryer (T, T') through said at least one feed port (205, 405), turbine The inner wall of the dryer is maintained at a temperature of at least 70° C. by the heating jacket, and the rotor rotates at a speed of at least 150 rpm; - centrifuging and propelling said wet powder within a turbo dryer by the action of said rotor; and - A continuous stream of oxidized starch-containing pulverulent material having a water content less than or equal to 20% by weight is discharged from the outlet (207, 407) of the turbo dryer. 12. The method according to claim 11, wherein a gas stream heated to a temperature of at least 50° C. A spout (206, 406) is also fed into the turbo dryer, wherein the gas stream is preferably an air stream. 13. The method according to claim 12, wherein the temperature of the inner wall of the turbo dryer (T, T') is maintained at 70-180° C., preferably 130-150° C., and the air flow into the turbo dryer The temperature is preferably between 50°C and 250°C, conveniently between 120°C and 150°C. 14. A method according to any one of claims 9 to 13, wherein said elements (9, 109, 209, 409) protruding radially from the shaft of the rotor are rods, vanes, V-shaped vanes or in the form of a blender. 15. The method according to any one of claims 9-14, wherein the w/v concentration of the aqueous hydrogen peroxide solution is between 5% and 20%. 16. The method of claim 15, wherein the w/v concentration of the aqueous ammonia solution is between 5% and 20%. 17. The method according to any one of claims 9-16, wherein the ratio between the flow rate of the aqueous hydrogen peroxide flow and the flow rate of the starch-containing pulverulent material flow is between 1: Between 20 and 1:5, preferably between 1:15 and 1:8. 18. The method according to claim 17, wherein the ratio between the flow rate of the aqueous ammonia solution flow and the flow rate of the starch-containing pulverulent material is between 1:20 and 1:5, preferably Earth is between 1:15 and 1:8. 19. The method according to any one of claims 9-18, wherein, by the drying step, the water content of the powdery material containing oxidized starch reaches less than or equal to that of the powdery material containing oxidized starch 5 to 15% by weight of the total weight of the material. 20. An apparatus for carrying out the method for oxidizing a starch-containing powdery material according to claim 9, comprising: a first reactor (R), comprising a cylindrical tubular body (1) with a horizontal axis, having at least one opening (5, 6) for the introduction of reagents and at least one opening (7) for the discharge of final product; an optional heating jacket or cooling jacket (4) for bringing the temperature of said tubular body to a predetermined temperature; and a rotor arranged in the cylindrical tubular body and comprising elements (9) provided with radially protruding therefrom axis(8); A second reactor (R'), comprising a cylindrical tubular body (101) with a horizontal axis, having at least one opening (105, 106) for the introduction of reagents and at least one opening (107) for the discharge of the final product an optional heating or cooling jacket (104) for bringing the temperature of said tubular body to a predetermined temperature; and a rotor arranged in the cylindrical tubular body and comprising elements (109) provided radially protruding therefrom ) axis (108). 21. An apparatus for carrying out the method for oxidizing a starch-containing powdery material according to claim 10, comprising: A reactor (R") comprising a cylindrical tubular body (301) with a horizontal axis, provided with a first opening (306) for introducing reagents and a second opening (306) arranged near one end of said cylindrical tubular body an opening (305) arranged at a position between said first end of said cylindrical tubular body and a third opening (310) for introducing a reagent, at least one for an opening (307) for discharging the final product; an optional heating or cooling jacket (304) for bringing the temperature of said tubular body to a predetermined temperature; and a rotor arranged in the cylindrical tubular body and comprising a The shaft (308) of its radially protruding element (309). 22. The plant according to claim 20, further comprising a turbo dryer (T) comprising a cylindrical tubular body (201) with a horizontal axis, having at least one inlet (205, 206) and at least one outlet a mouth (207); a heating jacket (204); and a rotor arranged in the cylindrical tubular body and comprising a shaft (208) provided with an element (209) protruding radially therefrom. 23. The plant according to claim 21, further comprising a turbo dryer (T') comprising a cylindrical tubular body (401) with a horizontal axis, having at least one feed inlet (405, 406) and at least one outlet A spout (407); a heating jacket (404); and a rotor arranged in the cylindrical tubular body and comprising a shaft (408) provided with an element (409) projecting radially therefrom. 24. The device of claim 22, further comprising: An injector device (51) having a tubular body provided with an inlet (7) fluidly connected to at least one outlet (7) of said first reactor (R), and an outlet (57) connected to said first reactor (R) at least one feed port (105) fluidly connected to two reactors (R'); a blade or screw rotor (58) supported within said tubular body; and An injector device (151) having a tubular body provided with an inlet (155) in fluid connection with at least one outlet (107) of said second reactor (R') and a discharge (157) with a turbine At least one feed port (205) of the dryer (R') is fluidly connected; a blade or screw rotor (158) supported within said tubular body. 25. The apparatus according to claim 23, further comprising an injector device (351) having a tubular body provided with an inlet (355) in fluid contact with at least one outlet (307) of said reactor (R") connection, as well as an outlet (357), fluidly connected with at least one feed port (405) of said turbo dryer (T"); a blade or screw rotor (358) supported within said tubular body. 26. A powdery material containing oxidized starch, which can be obtained by the method according to any one of claims 2-19 from the group consisting of: starch from corn, potato, wheat, cassava, rice and beans , meals from cereals such as wheat, rice, corn, barley, rye, oats, buckwheat, amaranth and quinoa, and from sources such as soybeans, peas, chickpeas, broad beans, lentils, lupines, sweet peas and soybeans Obtained from the powdery material in the group consisting of coarse meal of legumes.